Mark Zuckerberg’s net worth increased by $3 billion Tuesday as the Facebook CEO appeared before Congress to field questions following the recent Cambridge Analytica leak that exposed 87 million users’ data.

The highly-scrutinized testimony before the Senate Judiciary Committee, which marked the first time Zuckerberg appeared in person in front of Congress, did not deter investors. Facebook shares went up 4.5% to $165 from $157.93 the day before in the company’s most significant one-day gain in about two years. Facebook gained $21 billion in value to close at $479.4 billion.

Facebook’s gain reversed some of the company’s losses over the last month. After reports of the Cambridge Analytica leak emerged in March, Facebook’s stock tumbled, causing Zuckerberg to lose $10 billion in one week. On Tuesday, his net worth looked like it might bounce back.